Reports: UNI651208-UNI6: Insights into the Reaction Mechanism and Catalyst Efficiency of the Conversion of Alkanes to Fuel Alcohols and the Steam Reformation Process

Jonathan T. Lyon, Clayton State University

We are studying reactions between metal atoms and small
alkanes as well as metal atoms and fuel alcohols in order to understand the
reaction pathways and intermediates that form in the conversion of alkanes to
fuel alcohols (i.e., CnH2n+2 + ½ O2 →
CnH2n+1OH), and vice versa, on transition
metal catalysts. Our investigations combine theoretical techniques
to predict the stability of intermediate species and their molecular properties
with experiments to synthesize and trap reactive intermediates in an inert
argon matrix. Comparison between the two methods (i.e., theory and
experiment) will ultimately yield structural assignments of the intermediates
in the catalytic conversion between alkanes and alcohols.

Students working under the direction of the principle
investigator, Dr. Jonathan T. Lyon, have theoretically modeled the reaction
pathway from methanol to synthesis gas (CO + H2) on both an iron atom
and a vanadium atom acting as the catalyst. Synthesis gas can be
used to make many alkanes and fuel alcohols. Additionally, another
student has modeled the interaction of ethanol with an iron atom. Thus,
we have been able to compare differences in the reaction pathway for fuel
alcohols of differing sizes (i.e., methanol and ethanol) reacting with an iron
atom. In all three studies using density functional theory, the
lowest energy isomers are found to be the initial insertion products H-M-O-CH3 (M
= V, Fe) and H-Fe-O-CH2-CH3. For all species,
vibrational frequencies were calculated (Figure 1) and will be compared to our
future experimental observations.

During the past year, work has also been performed to
construct the experimental apparatus capable of performing the proposed matrix
isolation experiments. This apparatus will allow us to identify the
intermediates that form when transition metal atoms are reacted with methanol
and ethanol (Figure 2). Metal atoms will be generated by laser
ablation using an Nd:YAG laser purchased using funds provided by this PRF award. The
metal atoms will be co-deposited with a dilute mixture of fuel alcohols (i.e.,
methanol and ethanol) in argon onto a ~10 K CsI window, which is
cooled by a liquid helium cryostat. Once a large enough concentration accumulates
on the window, the intermediates will be observed using infrared spectroscopy. The
reaction and deposition is carried out in a vacuum chamber which will be pumped
to ~10-6 torr during the experiments. After
deposition, the matrix will be exposed to several annealing cycles as well as
UV radiation. Infrared spectra will be collected after deposition
and after the matrix is exposed to each thermal and/or radiation treatment.
Different IR peaks can be grouped and attributed to specific species within
the accumulated argon matrix based on the behavior of the
absorptions. The experimental frequencies for a given group will be
compared to those predicted by theory for several isomers. It is
expected that the vibrational structure predicted for the lowest energy isomers
will be observed in the experimental spectra, confirming our theoretical predictions.

Select preliminary results of this study were presented by
the principle investigator and an undergraduate student (Mr. Marcus Bartlett,
Chemistry 2013) at the 2011 Southeastern Regional Meeting of the American
Chemical Society (SERMACS) in Richmond, VA. This PRF grant has
financially supported two undergraduate students (Mr. Patrick Drew, Chemistry
2012 and Mr. Marcus Bartlett, Chemistry 2013). Additionally, a high school
student who was supported by an ACS SEED project award (Ms. Minh-Thu Phan)
has participated in the project. All three students have presented
their results at least once during the past year to faculty and students on
Clayton State University's campus (e.g., at the Department of Natural Sciences
end of semester Research Presentations, the university wide Academic Conference,
or both). The principle investigator and students are sincerely grateful
for the financial support from the ACS Petroleum Research Fund which has aided in
establishing a productive research program for undergraduate students at
Clayton State University.